Computer-aided design (CAD) software allows a user to construct and manipulate complex three-dimensional (3D) models. A number of different modeling techniques can be used to create a 3D model. One such technique is a solid modeling technique, which provides for topological 3D models where the 3D model is a collection of interconnected topological entities (e.g., vertices, edges, and faces). The topological entities have corresponding supporting geometrical entities (e.g., points, trimmed curves, and trimmed surfaces). The trimmed surfaces correspond to the topological faces bounded by the edges. CAD systems may combine solid modeling and other modeling techniques, such as parametric modeling techniques. Parametric modeling techniques can be used to define various parameters for different features and components of a model, and to define relationships between those features and components based on relationships between the various parameters.
A design engineer is a typical user of a 3D CAD system. The design engineer designs physical and aesthetic aspects of 3D models, and is skilled in 3D modeling techniques. The design engineer creates parts and may assemble the parts into a subassembly or an assembly. A subassembly may also consist of other subassemblies. An assembly is designed using parts and subassemblies. Parts and subassemblies are hereinafter collectively referred to as components.
When designing an assembly, a design engineer may need to incorporate a standard part in a subassembly or an assembly model. Rather than re-designing a standard part, the part may be retrieved from a database of existing parts. Commercially available component databases contain CAD models for standard physical parts. Such databases are referred to as part libraries. Fully integrated with the SOLIDWORKS® 2013 software system available from Dassault Systèmes SolidWorks Corporation of Waltham, Mass. is the SOLIDWORKS Toolbox, which is an example of a commercially available part library. The SOLIDWORKS Toolbox includes standard parts such as common fasteners (e.g., bolts, screws, washers, and nuts), each of which geometrically represents a real-world fastener in a CAD model. The SOLIDWORKS Toolbox fasteners have spatial and mass property attributes that aid in the design of a real-world object.
In current state-of-the-art CAD systems, when the design engineer inserts a fastener into a CAD model, the design engineer may wish to establish a constraint to attach the fastener part to one or more other parts in the CAD model. Such constraints are referred to as mating relationships.
Current approaches to creating mating relationships include geometry-based solutions and predetermined mate-reference solutions. Geometry-based solutions allow a design engineer to select and drag, using a pointing device such as a mouse, or otherwise specify a particular geometry to be mated. The SmartMates tool, available in SOLIDWORKS software, provides for a geometry-based solution, which can determine that a circular edge on one component and a circular hole pattern on a second component have the same radius and then add a concentric mate to align the circular edge with the circular pattern.
Predetermined mate-reference solutions, such as is implemented in SOLIDWORKS® 2013 software, allow a design engineer to manually define a constrained relationship prior to a part being incorporated into a CAD model through selections and specifications of mates likely to be needed later. Thus, a design engineer may define how a part will be mated before the part is inserted into an assembly as a component of that assembly. Predetermined mate-references accelerate the mating process by not requiring the selection of entities while mating a component into an assembly. Once the definition is completed, components can be constrained automatically if certain conditions are met.
During the design process, an engineer may simulate the design of a model to analyze and evaluate the real-world performance of the product being designed. Such a simulation may be executed by an engineering simulation process, examples of which are SOLIDWORKS Simulation Xpress and SOLIDWORKS Simulation, which use the CAD model data to set up and execute simulation studies. Fasteners created during the design process are often excluded from simulation studies. Excluding the fasteners, in general, increases the execution speed of a simulation. However, a type of relationship in a modeling environment that includes a fastener differs from the type of relationship needed for a simulation study, as will be explained. The former relationship is typically a mating relationship based on geometric fit; whereas, the later relationship should, in many cases, be treated as a connection influencing the interaction between a fastener or fastener stack (which is a combination of two or more fasteners), and another part or one or more features thereof. Thus, in general, during a simulation of components, the design engineer manually substitutes fastener data used in a modeling environment with the appropriate fastener data for a simulation environment, which is a simulation-specific abstraction of the fastener that allows for the effect of fastening components together and the influence of a fastener on other components without the use of the fastener geometry.
For example, a threaded bolt fastener used in a simulation study is a mathematical representation of the influence of the threaded fastener on a CAD model. Without a simulation bolt fastener, a design engineer would have to make assumptions, which may be invalid, to simulate a threaded fastener between two components. If a mathematical representation of the fastener's influence is not available or if the design engineer wishes to use another representation, the design engineer could bond the two components that would be bolted together or include the fastener geometry in the simulation.
Bonding is an operation used in a simulation environment that ensures the continuity of a model to transfer loads between two entities. Using SOLIDWORKS Simulation software, an end-user may bond a face or an edge to any other face or edge, for example. Bonding the components may be highly inaccurate, however; for example, the simulation solver may consider two one-inch thick bonded plates as one two-inch thick plate, and stresses and displacements may be significantly different when two plates are bonded as opposed to bolted to one another.
Including the fastener geometry in the simulation may be prohibitive computationally and memory intensive for a very simple model (e.g., a difference between days of computational time versus minutes). In general, a design engineer may be required to expend considerable computational effort to include the actual fastener geometry in the simulation because more contact conditions need to be defined between the fastener and the mating components.
A CAD system that requires a design engineer to create two types of objects that represent the same part—one during the CAD modeling process and one to execute a simulation process lacks efficiencies that would be beneficial in a CAD modeling system.
Currently available technologies fall short of the solutions later to be described herein for various reasons. Such solutions allow for time-saving advantages and enhancements to current CAD systems, achieved by providing more efficient means for transferring data between a modeling environment and a simulation environment.